III-Nitride devices are normally-on depletion mode (D-mode) devices. A negative voltage is applied to the gate of the device to turn it off. In a typical III-Nitride device, an AlGaN layer atop a GaN layer forms a 2 DEG, normally conductive layer which conducts under a control gate and between a source and a drain electrode atop and in contact with the AlGaN layer.
However, leakage paths exist in the GaN layer which is normally relatively highly doped. The device also suffers from sub-threshold characteristics and relatively poor transconductance characteristics.
It would be desirable to provide a III-Nitride device which improves the leakage, the subthreshold characteristics and transconductance of such devices while employing well known processing techniques for its manufacture.